This invention relates to tool components.
Abrasive compacts are well known in the art and are used for a variety of abrading operations such as cutting, drilling, grinding, and the like. Abrasive compacts consist of a polycrystalline mass of bonded abrasive particles, the abrasive particle content of which is at least 70 percent by volume, and generally 80 to 90 percent by volume. The abrasive particles may be self-bonded without the aid or use of a second or bonding phase. Alternatively, a second or bonding phase may be provided. The abrasive particles for compacts are invariably diamond or cubic boron nitride.
Abrasive compacts may be bonded to cemented carbide supports. Such bonded compacts are often referred to as composite compacts. bonding between the compact and the carbide support may be direct, i.e. without the interposition of a braze layer. Alternatively, a bonding braze layer may be provided between the compact and the carbide support. A more detailed description of abrasive compacts and composite abrasive compacts may be found in a number of published patent specifications, for example, U.S. Pat. Nos. 3,743,489, 3,767,371, 4,063,909 and 3,745,623.
Rotary drills used for oil and gas well drilling and core drilling generally comprise a drill bit having formed thereon a plurality of pre-formed sockets in which cutting elements or components are mounted. The cutting elements or components may be brazed, force-fitted or heat shrunk into the sockets. Typical cutting elements used in the prior art are steel teeth, steel teeth laminated with tungsten carbide, inserts of cemented tungsten carbide, natural diamonds and composite abrasive compacts.
Cutting components for drill bits and utilising composite compacts have been described in the literature and have been used commercially. Such cutting components comprising an elongate pin of cemented carbide to which is bonded a composite compact, bonding being achieved through the carbide support of the composite compact. Bonding between the carbide support and the elongate pin is achieved by braze metal which has a melting point above 700.degree. C. Such a high temperature braze, so the art teaches, is essential in order to achieve a sufficiently strong bond between the composite compact and the elongate pin. Reference in this regard may be had to disclosures of U.S. Pat. No. 4,225,322. The braze which is said in this patent specification to be useful is Anaconda 773 which is now thought to be undesirably reactive with the carbide pieces being joined.
European Patent Publication No. 213,300 and U.S. Pat. No. 4,527,998 describe braze alloys for bonding composite abrasive compacts to elongate pins which are said to have advantages over Anaconda 773. The alloy of the European publication contains palladium, chromium, boron and nickel while the alloy of the United States patent contains gold, nickel, palladium, manganese and copper.
Tool components are also available and used which comprise two carbide bodies bonded together or a carbide body bonded to a steel or like body. Strong bonds between such bodies are desirable.